Acoustic telephone



(No Model.)

O. D. BENTLEY.

AQOUSTIG TELEPHONE. No. 334,069. atented Jan; 12, 1886.

i 5 IL I 1 Mn WWI- a l k I 1* Ii WIT/V5885 IIVI/E/VTOR By M/Hforneys UNITED STATES PATE T OFFICE.

CHARLES D. BENTLEY, OF EATON tAPlDS, MICHIGAN.

ACOUSTIC T ELEPHONE.

SPECIFICATION forming part of Letters Patent No. 33 L069, dated Januaiy 12, 1886.

Application filed June 1, 1885.

T0 (LZZ whom, it may concern:

Be it known that 1, CHARLES D. BENTLEY, a citizen of the United States, residing at Eaton Rapids, in the county of Eaton and State of Michigan, h'aveinvented a new and useful Improvement in Acoustic Telephones, of which the following is a specification, reference being had to the accompanying drawings.

This invention relates to acoustictelephones, and has for its object to improve the construction of the same, enabling them to work with greater eiiieiency by securing a remarkable clearness of enunciation and fineness of tone not oft-en found in this class of instruments.

Vith these ends in view the said invention consists in certain details of construction and combination of parts, as will be hereinafter set forth, and particularly pointed out in the claims.

In the accompanying drawings, Figure 1 is a side elevation showing my improved telephone applied in position. Fig. 2 is a vertical longitudinal section of the same. Fig. 3 is a horizontal section on the line 00 m, Fig. 2. Fig. 4 is an elevation of the back piece which secures the telephone to the wall.

Like letters are used to indicate corresponding parts in the several figures.

Referring to the drawings, A designates the mouth-piece, which hasa central aperture for the passage of the sound-waves.

B designates the bed-piece, which formsthe sounding'chamber, and is secured to the rear face of the mouthpiece by screws or other suitable fastenings to form the speaking and hearing cups.

Interposed between the two parts A B, at their point of junction, are a pair of dia-- phragms, G D, the outer diaphragm, 0, being constructed of metal, and the inner diaphragm, D,,being made of thin pasteboard or heavy paper. These diaphragms are placed flat against each other, and are held in position by the screws which pass through the parts A B. A central perforation or opening is provided through each of the diaphragms for the passage of the line-wire E, on the end of which is secured the usual button, F, the latter bearing against the outer metallic diaphragm, 0, when the telephone is in use.

The bed-piece B has its interior hollowed out to form a soundingchamber, G, and is Serial No. 167241.

provided with a central opening for the passage of the line-wire. The walls of the sounding-chamber are corrugated, as shown at a Z), the interior diameter of the chamber being less at the point where the corrugation b is formed, while it is greater at the corrugation a. The corrugation a is deeper than the corrugation l), and coincides with the line or wall of the central aperture for the mouth-piece. By this construction the sound-waves are collected in the chamber and delivered upon the diaph a from whence they a1 e transmitted to the month-piece A, which also forms th cup or receiver, as will be readily understood. The peculiar construction of the sound-chamber 1 Wiates the discordant or rumbling sou ds in the receiver, so common to this class of instruments, and makes the articulation more clear and distinct. The mixing of sounds in the receiver is also entirely obviated.

I designates a fiat curved springplate, having its central depressed portion secured to the back piece, J, and its ends 0 working through staples or bails K, projecting from the rear face of the bed-piece B, near the up perend thereof. This back piece,J,issecnred by screws or other fastening means to the wall or other portion of the room, and is made of sutticient length to project above and below the telephone proper, the form of this piece being shown in Fig. 4. A coiled spring, L, is secured to the back piece, near the lower end thereof, and bears against the inner or rear face of the bedpiece B. A central opening, (1, is provided in the back piece,J for the passage of the line-wire E. Depending from the bed-piece B is a spring-hanger, M, which carries a bell or other alarm, as at N, which is used to signal from one end of the line to the other in the usual manner. It will be observed that the telephone proper is suspended from the wall solely by the springplate I, while its lower end is retained at a proper distance from the back piece by the coiled spring L. By this connection I am enabled to take up the expansion of the linewire, and since the attachment is made yielding it will prevent the breakage of the line should the wire suddenly contract, as is sometimes the case.

The operation of my invention will be readily understood from the foregoing description, taken in connection with the annexed drawings. To use the telephone, it is only necessary to strike the mouth-piece at apoint over or on a line with the coiled spring L, causing the telephone to yield inward and instantly rebound, drawing the line-wire outward, and thus causing the telephone at the other end of the wire to be shaken or vibrated and efiecting the ringing of its bell in a manner well known. The call being answered in the same manner, the conversation takes place as in other acoustic telephones. The bell should be so placed or connected that the least vibration of either the speaking or hearing cup or telephone will draw the line-wire to give the signal at the other cup. The springplate I,which is attached to the back piece,J,

' works loosely at its end, so that when the cup is pressed inward this plate works outward through the bails K, and when pressure is removed from the cup this plate returns to its normal position, causing the cup to rebound or work outward, as will be readily understood. The spring L, which bears against the rear face of the cup, retainsthe latter at a proper distance from the back piece, said spring yielding when the cup is pressed inward, and then automatically expanding to restore the cup to its former position. The spring-plate I works in connection with the coiled spring L to retain the required tension of the linewire. The spring-plate carries the greater portion of the weight of the telephone-cup, while the coiled spring retains the cup in a vertical line parallel with the back piece.

By the employment of a metallic diaphragm, O, I am enabled to connect it with a battery so as, to adapt the telephone for use at long distances. The pasteboard diaphragm D gives the wire a sharp distinct sound, and also operates to prevent the ringing sound in metallic heads when the line-wire has to be strained taut. This pasteboard diaphragm being secured on the inner face of the metallic diaphragm, and between it and the soundingchamber, serves to receive and transmit speech with greater clearness than with other telephones of this kind. Since the metallic diaphragm receives the pressure from the button, the telephone is enabled to sustain or resist the tension of the line-wire. The combination of the two diaphragms, in connection .with the peculiar construction of the soundingchamber, enables me to provide a telephone which will have remarkable sounding qualities, without that indistinct articulation so often objected to by those having occasion to use telephones of this character.

Having described my inventiom, I claim 1. In an acoustic telephone, the speaking and hearing 'cups having a bell connected thereto, in combination with a spring-plate rigidly connected at its center to the wall or other support, and having its ends fitted to the cups so as to yield outward when the latter are pressed inward, as set forth.

2. In an acoustic telephone, the speaking and hearing cups having a bell connected thereto, in combination with a rigidly-fastened spring-plate attached to the wall or other support, and having a yielding connection with the cup and forming the sole support for the same, as set forth.

3. In an acoustic telephone, the speaking and hearing cups having a bell connected thereto, in combination with the spring-plate connected near the upper ends of the cups, and a spring bearing against the lower ends, so as to retain the cupsin the "ertical position and obviate the necessity ofhinging the cups, as set forth.

4. In an acoustic telephone, the speaking and hearing cups having a bell connected thereto, in combination with a spring-plate rigidly connected to the center and working through guides at its ends, as set forth;

5. In an acoustic telephone, the mouth-piece A, in combination with the bed-piece B, hollowed out to provide a sounding-chamber, and the double diaphragm having its edges received between the parts A B at their point of connection and held in place by the same securing means. thesection of the diaphragm facing the sounding-chamber being constructed of pasteboard or the like, so as to transmit speech from the said chamber, while the other section is made of metal, the line-wire being passed through the sounding-chamber and the double diaphragm, and having the button pressing against the metallic section, whereby the latter will be enabled to withstand the tension placed-on the wire, as set forth.

In testimony that I claim the foregoing as my own I have hereto affixed my signature in presence of two witnesses.

CHARLES D. BENTLEY.

Witnesses:

H. H. HAMILTON, W. F. STIRLING. 

